This is a relay box for 1 channel relay modules such as this one To assemble it, you will need four 18mm M3 machine bolts. Hook up the AC side of the relay module, clip it into the bottom portion and screw the top piece in place. Now you can hook up some jumper wires from the outside and you are good to go.

I uploaded two Versions of the top piece. One with an Inlay and one without. If you want to print two colors with a single extruder printer, like my Anet A8, check out this video by "Make Anything".